During cardiac bypass surgery a patient's heart is slowed or stopped for surgical repair, and his or her blood must be artificially oxygenated and pumped through the body using an extracorporeal support circuit. Using this system, venous blood is diverted from entering the right chambers of the heart and is instead directed through a series of tubes, pumps and filters, which provide fresh oxygen to the blood and return it to the body's systemic circulation at the aorta. The oxygenated blood is then circulated throughout the body. The circuit thus ensures that the patient continues to be nourished by oxygenated blood flow while the heart is unable to function.
In performing such a procedure, a complicated apparatus is required. One or two blood reservoirs, an oxygenator (possibly combined with a heat exchanger), a blood pump, and multiple tubes to connect the various components are needed and must be assembled and arranged before surgery may begin. Typically a significant amount of time must be spent just prior to surgery to accomplish the set-up, and great attention must be paid to the details of this complicated task.
In a conventional extracorporeal support circuit, a venous line drains blood from the right side of the patient's heart and delivers it to a blood reservoir. The blood is then pumped by a specially designed pump from the outlet of the blood reservoir into a blood oxygenator for oxygenation and cooling. The oxygenated blood is artificially pumped via an arterial line to the venous line, and the circuit is continued in this fashion until the surgical repair is complete.
The support circuit normally includes a blood scavenging sub-circuit for recovering and recycling blood from the surgical field. The sub-circuit includes one or more suckers (typically two to four) for sucking blood from the surgical field. Vacuum is applied to the suckers by a peristaltic positive displacement pump (also known as a roller pump) or wall vacuum to deliver the scavenged blood to a cardiotomy reservoir. The reservoir includes a defoaming section to remove entrained air and a filter. The outlet for the cardiotomy reservoir delivers the de-foamed, filtered blood to the venous reservoir of the main circuit. Various cardiotomy reservoirs are described in U.S. Pat. Nos. 3,891,416, 3,993,461, 4,208,193 and 4,243,531. The cardiotomy reservoir may alternatively be an integral portion of the venous blood reservoir in which the scavenged blood flows through a filter section and the venous blood does not.
A schematic diagram of a conventional extracorporeal support system is shown in FIG. 1. A reservoir 20 is provided for cleaning, debubbling, and collecting the blood. A tubing assembling called a pump loop 22 includes a pump inlet line 24 and a pump outlet line 26. These two lines are connected to an arterial pump 28, which for the purposes of this invention will most conveniently be of the type which has a pump header 30 which is separable from the motor portion. The pump outlet 26 leads to the inlet of the oxygenator 32, which may include a heat exchanger 34.
The elements so far described are connected to the body of the patient by a tubing assembly called an A-V loop 36. The A-V loop 36 includes a venous line 38 to carry the patient's low-pressure, oxygen depleted venous blood to the reservoir, and an arterial line 40 carrying high-pressure, oxygen rich arterial blood from the oxygenator 32 back to the patient. It may be convenient to monitor the condition of the blood in these two lines, so a blood parameter monitor 42 may be provided having sensors 44 and 46, which are kept in chemical equilibrium with the blood flowing in the venous line 38 and the arterial line 40, respectively. A hematocrit monitor 48 may also be provided, having its own sensor 50, conveniently monitoring the blood in the venous line 38.
It may be convenient to perfuse the patient's heart directly with a different solution than is provided to the rest of the patient's body. Cardioplegia solution is typically used in this fashion to slow or stop the patient's heart during surgery. A cardioplegia pump 52 may be used to deliver cardioplegia solution supplied by solution line 56 from a solution supply 58. The cardioplegia pump outlet line 60 passes through a cardioplegia heat exchanger 62 and a bubble trap 64 before delivering cardioplegia solution to the heart at the cardioplegia catheter 66.
Two suction lines are typically provided to recapture blood from the site of the surgical incision that has escaped the closed system. The first is called the vent line 68, and runs from a vent catheter 70 through a vent pump 72 to the reservoir 20. The second is called the suction line 74, and runs from a suction device 76 through a suction pump 78 and once again to the reservoir 20.
To prepare the system for use, each of the tubing connections must be individually made by a skilled person in the operating room. Many of these connections are between disposable system components, such as tubes and filters, which could advantageously be pre-connected and assembled in an assembly pack for quick attachment to the nondisposable elements of the system, thus enhancing operating room efficiency. However, no such assembly packs have heretofore been developed in the art.